US20150050750A1 - Plasma processing method and plasma processing apparatus - Google Patents
Plasma processing method and plasma processing apparatus Download PDFInfo
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- US20150050750A1 US20150050750A1 US14/387,655 US201314387655A US2015050750A1 US 20150050750 A1 US20150050750 A1 US 20150050750A1 US 201314387655 A US201314387655 A US 201314387655A US 2015050750 A1 US2015050750 A1 US 2015050750A1
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- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
- H01L21/306—Chemical or electrical treatment, e.g. electrolytic etching
- H01L21/3065—Plasma etching; Reactive-ion etching
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- H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
- H01J37/32082—Radio frequency generated discharge
- H01J37/32091—Radio frequency generated discharge the radio frequency energy being capacitively coupled to the plasma
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- H01J37/32—Gas-filled discharge tubes
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- H01J37/32082—Radio frequency generated discharge
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- H01J37/32—Gas-filled discharge tubes
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- H01J37/32798—Further details of plasma apparatus not provided for in groups H01J37/3244 - H01J37/32788; special provisions for cleaning or maintenance of the apparatus
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- H01J37/32431—Constructional details of the reactor
- H01J37/32798—Further details of plasma apparatus not provided for in groups H01J37/3244 - H01J37/32788; special provisions for cleaning or maintenance of the apparatus
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- H01J37/32431—Constructional details of the reactor
- H01J37/32798—Further details of plasma apparatus not provided for in groups H01J37/3244 - H01J37/32788; special provisions for cleaning or maintenance of the apparatus
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- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/02—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components specially adapted for rectifying, oscillating, amplifying or switching and having at least one potential-jump barrier or surface barrier; including integrated passive circuit elements with at least one potential-jump barrier or surface barrier
- H01L27/04—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components specially adapted for rectifying, oscillating, amplifying or switching and having at least one potential-jump barrier or surface barrier; including integrated passive circuit elements with at least one potential-jump barrier or surface barrier the substrate being a semiconductor body
- H01L27/10—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components specially adapted for rectifying, oscillating, amplifying or switching and having at least one potential-jump barrier or surface barrier; including integrated passive circuit elements with at least one potential-jump barrier or surface barrier the substrate being a semiconductor body including a plurality of individual components in a repetitive configuration
- H01L27/105—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components specially adapted for rectifying, oscillating, amplifying or switching and having at least one potential-jump barrier or surface barrier; including integrated passive circuit elements with at least one potential-jump barrier or surface barrier the substrate being a semiconductor body including a plurality of individual components in a repetitive configuration including field-effect components
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- H01J2237/32—Processing objects by plasma generation
- H01J2237/327—Arrangements for generating the plasma
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- H01J2237/32—Processing objects by plasma generation
- H01J2237/33—Processing objects by plasma generation characterised by the type of processing
- H01J2237/334—Etching
- H01J2237/3341—Reactive etching
Abstract
A plasma processing method of etching a multilayered material having a structure where a first magnetic layer 105 and a second magnetic layer 103 are stacked with an insulating layer 104 therebetween is performed by a plasma processing apparatus 10 including a processing chamber 12 where a processing space S is formed; and a gas supply unit 44 of supplying a processing gas into the processing space, and includes a first etching process where the first magnetic layer is etched by supplying a first processing and generating plasma, and the first etching process is stopped on a surface of the insulating layer; and a second etching process where a residue Z is removed by supplying a second processing gas and generating plasma. The first magnetic layer and the second magnetic layer contain CoFeB, the first processing gas contains Cl2, and the second processing gas contains H2.
Description
- The embodiments described herein pertain generally to a plasma processing method and a plasma processing apparatus.
- In Patent Document 1, a kind of plasma processing method is described. In this plasma processing method, a MRAM device is manufactured by processing a multilayered object including a magnetic tunnel junction (MTJ) in which an insulating layer is interposed between a lower magnetic layer and an upper magnetic layer. In this method, Al2O3 is used as a material of the insulating layer. A magnetization direction of the lower magnetic layer is fixed, but a magnetization direction of the upper magnetic layer is changed by an external magnetic field. To be specific, in the method described in Patent Document 1, the MRAM device is manufactured by (a) forming a first mask on an upper electrode layer, (b) plasma-etching the upper electrode layer, the upper magnetic layer, and the insulating layer, (c) removing the first mask, (d) forming a second mask on the upper electrode layer, and (e) etching a lower electrode layer.
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- Patent Document 1: Specification of U.S. Patent Application Publication No: US 2004/0137749
- In an apparatus described in Patent Document 1, when the multilayered object is etched, a residue containing a conductive material may adhere to a side wall of the insulating layer. If the residue adheres to the side wall of the insulating layer, a leakage current is generated at the MTJ so that characteristics of the MRAM device are deteriorated. In order to solve such a problem, it is considered that the residue is suppressed from adhering to the side wall of the insulating layer by stopping the etching process on a top surface of the insulating layer. In the case of performing this method, it is necessary to increase etching selectivity between the magnetic layer and the insulating layer.
- Meanwhile, it is known that if MgO is used as a material of the insulating layer of the MTJ device, a high MR ratio can be obtained. However, since MgO is a new material for the insulating layer of the MTJ device, there are not known etching conditions in which a high selectivity between the magnetic layer and the insulating layer made of MgO can be obtained. Therefore, in this technical field, there is a demand for stopping the etching process on the top surface of the insulating layer even when MgO is used for the insulating layer and improving the characteristics of the MRAM device by suppressing a leakage current from being generated.
- In one example embodiment, a plasma processing method of etching a multilayered material having a structure in which a first magnetic layer and a second magnetic layer are stacked with an insulating layer interposed therebetween is performed by using a plasma processing apparatus including a processing chamber in which a processing space for plasma generation is partitioned and formed; and a gas supply unit of supplying a processing gas into the processing space. The plasma processing method includes a first etching process in which the first magnetic layer is etched by supplying a first processing gas into the processing chamber and generating plasma, and the first etching process is stopped on a surface of the insulating layer; and a second etching process in which a residue produced in the first etching process is removed by supplying a second processing gas into the processing chamber and generating plasma. The first magnetic layer and the second magnetic layer contain CoFeB, the first processing gas contains Cl2, and the second processing gas contains H2.
- In the plasma processing method in accordance with the example embodiment, in the first etching process, the first magnetic layer is etched by supplying the first processing gas containing Cl2 and generating plasma, and then, the first etching process is stopped on the surface of the insulating layer. Cl2 reacts with CoFeB contained in the first magnetic layer, but does not react with MgO contained in the insulating layer. Thus, etching selectivity between the magnetic layer containing CoFeB and the insulating layer containing MgO can be improved. Further, according to this plasma processing method, in the second etching process, the residue adhering to the side surfaces of the first magnetic layer and the top surface of the insulating layer is removed with the etching gas containing H2. Thus, the verticality of the first magnetic layer is improved, and it is possible to suppress a residue from being dispersed and adhering to the side walls of the insulating layer when etching the insulating layer to be described later. Therefore, in accordance with the plasma processing method of the example embodiment, it is possible to improve characteristics of the MRAM device by suppressing the leakage current.
- In the example embodiment, the second processing gas may further contain at least one of N2, Ar, and He. In this case, it is possible to surely remove the residue adhering to the side surfaces of the first magnetic layer and the top surface of the insulating layer.
- In the example embodiment, the plasma processing method may further include a coating process in which a surface of the multilayered material is coated with an insulating film after the second etching process. In this case, it is possible to surely suppress a residue from adhering to the side walls of the insulating layer in the subsequent process.
- In the example embodiment, the plasma processing method may further include a third etching process in which the insulating layer and the second magnetic layer are etched by supplying a third processing gas into the processing chamber and generating plasma, after the coating process. Further, the third processing gas may contain CH4. In this case, the MRAM device can be manufactured from the multilayered material.
- In the example embodiment, the plasma processing apparatus may further include a first electrode provided within the processing chamber; a second electrode provided to face the first electrode; a first power supply unit configured to apply a power having a first frequency to the first electrode; and a second power supply unit configured to apply a power having a second frequency to the second electrode. Further, the plasma may be generated within the processing chamber by applying a power having 1 MHz or less as the second frequency from the second power supply unit to the second electrode. In this case, since the power having the relatively low frequency is applied to the second electrode, the plasma is generated at a position spaced from the target object. Thus, the vertical movement of ions attracted by the second electrode is improved, and the verticality of the side wall of the target object can be improved accordingly.
- In the example embodiment, the plasma may be generated within the processing chamber by applying a power having 400 kHz or less as the second frequency from the second power supply unit to the second electrode. In this case, since the power having the relatively low frequency of 400 kHz is applied to the second electrode, the plasma is generated at a position spaced from the target object. Thus, the verticality of the side wall of the multilayered material to be etched can be improved.
- In the example embodiment, the plasma may be generated within the processing chamber by applying a power of 100 W to 300 W from the first power supply unit to the first electrode. In this case, since the relatively low power is applied to the first electrode, low-density plasma is generated at a lower limit of the margin of plasma ignition, and for example, the etched insulating layer or second magnetic layer can be discharged to the outside in the form of an organic metal complex having a large molecular structure.
- In the example embodiment, the plasma processing apparatus may further include an exhaust unit configured to depressurize the processing space to a predetermined pressure level; and a control unit configured to control the exhaust unit. Further, the control unit may be configured to control the exhaust unit to set a pressure inside the processing space to be in a range of 10 mTorr to 30 mTorr (1.33 Pa to 4.00 Pa). In this case, since the pressure inside the processing space S is set to be low, a density of plasma generated in the processing space can be reduced. As a result, since an ion mean free path is lengthened, the verticality of the etching profile can be improved.
- In the example embodiment, the processing space may have a gap of 20 mm to 30 mm. With this configuration, a sputtering effect can be increased, so than the exhaust for a low residence time (short staying time) can be promoted.
- In another example embodiment, a plasma processing apparatus etches a multilayered material having a structure in which a first magnetic layer and a second magnetic layer are stacked with an insulating layer interposed therebetween. Here, the plasma processing apparatus includes a processing chamber in which a processing space for plasma generation is partitioned and formed; a gas supply unit configured to supply a processing gas into the processing space; and a control unit configured to control the gas supply unit. Further, under the control of the control unit, the first magnetic layer is etched by supplying a first processing gas into the processing chamber and generating plasma, and then, the etching is stopped on a surface of the insulating layer; and a residue produced in the etching with the first processing gas is removed by supplying a second processing gas into the processing chamber and generating plasma. Moreover, the first magnetic layer and the second magnetic layer contain CoFeB, the first processing gas contains Cl2, and the second processing gas contains H2.
- In the plasma processing apparatus in accordance with the example embodiment, under the control of the control unit, the first magnetic layer is etched by supplying the first processing gas containing Cl2 and generating plasma, and the etching is stopped on the surface of the insulating layer. Cl2 reacts with CoFeB contained in the first magnetic layer, but does not react with MgO contained in the insulating layer. Thus, etching selectivity between the magnetic layer containing CoFeB and the insulating layer containing MgO can be improved. Further, under the control of the control unit, the residue adhering to the side surfaces of the first magnetic layer and the top surface of the insulating layer is removed with the etching gas containing H2. Thus, the verticality of the first magnetic layer is improved, and it is possible to suppress a residue from being dispersed and adhering to the side walls of the insulating layer when etching the insulating layer to be described later. Therefore, in accordance with the plasma processing apparatus of the example embodiment, it is possible to improve characteristics of the MRAM device by suppressing the leakage current.
- In accordance with the example embodiments, it is possible to improve characteristics of the MRAM device by suppressing the leakage current.
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FIG. 1 is a diagram schematically showing an example of a MRAM device manufactured by a plasma processing method in accordance with an example embodiment. -
FIG. 2 is a cross sectional view showing a plasma processing apparatus in accordance with the example embodiment. -
FIG. 3 is a flowchart showing the plasma processing method in accordance with the example embodiment. -
FIG. 4 shows a process of manufacturing the MRAM device using the plasma processing method in accordance with the example embodiment. -
FIG. 5 shows a process of manufacturing the MRAM device using the plasma processing method in accordance with the example embodiment. -
FIG. 6 shows a process of manufacturing the MRAM device using the plasma processing method in accordance with the example embodiment. -
FIG. 7 shows a process of manufacturing the MRAM device using the plasma processing method in accordance with the example embodiment. -
FIG. 8 shows a process of manufacturing the MRAM device using the plasma processing method in accordance with the example embodiment. -
FIG. 9 shows a process of manufacturing the MRAM device using the plasma processing method in accordance with the example embodiment. -
FIG. 10A andFIG. 10B are schematic diagrams of SEM images of target objects obtained from a first experimental example and a comparative example, respectively. -
FIG. 11 is a schematic diagram of a TEM image of the target object obtained from the first experimental example. -
FIG. 12A andFIG. 12B are schematic diagrams of SEM images of target objects obtained from a second experimental example and a comparative example, respectively. -
FIG. 13A andFIG. 13B are schematic diagrams of SEM images of target objects obtained from a third experimental example and a comparative example, respectively. -
FIG. 14 is a schematic diagram of a TEM image of the target object obtained from the third experimental example. - Hereinafter, various example embodiments will be explained with reference to the accompanying drawings. Further, in the drawings, similar symbols typically identify similar components, unless context dictates otherwise.
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FIG. 1 is a cross sectional view of aMRAM device 100 manufactured by a plasma processing method in accordance with an example embodiment. TheMRAM device 100 depicted inFIG. 1 is provided on a substrate B and includes alower electrode layer 101, a pinninglayer 102, a secondmagnetic layer 103, an insulatinglayer 104, a firstmagnetic layer 105, anupper electrode layer 106, and anetching mask 107 stacked in sequence from the bottom. Further, an insulatingfilm 108 is formed at side walls of the firstmagnetic layer 105, theupper electrode layer 106, and theetching mask 107 of theMRAM device 100. - The
lower electrode layer 101 is formed on the substrate B as an electrode member having electrical conductivity. Thelower electrode 101 has a thickness of, for example, about 5 nm. The pinninglayer 102 is provided between thelower electrode layer 101 and the secondmagnetic layer 103. The pinninglayer 102 is configured to fix a magnetization direction of thelower electrode layer 101 with a pinning effect caused by an antiferromagnetic material. The pinninglayer 102 is made of an antiferromagnetic material such as IrMn (iridium manganese), PtMn (platinum manganese), etc., and has a thickness of, for example, about 7 nm. - The second
magnetic layer 103 is provided on the pinninglayer 102 and contains a ferromagnetic material. The secondmagnetic layer 103 functions as a so-called “pinned layer” of which a magnetization direction is maintained uniformly without being affected by an external magnetic field with the pinning effect caused by the pinninglayer 102. The secondmagnetic layer 103 is made of CoFeB and has a thickness of, for example, about 2.5 nm. - The insulating
layer 104 is interposed between the secondmagnetic layer 103 and the firstmagnetic layer 105. Since the insulatinglayer 104 is interposed between the secondmagnetic layer 103 and the firstmagnetic layer 105, a tunnel magnetoresistance is generated between the secondmagnetic layer 103 and the firstmagnetic layer 105. That is, between the secondmagnetic layer 103 and the firstmagnetic layer 105, an electrical resistance is caused by a relative relationship (parallel or antiparallel) between a magnetization direction of the secondmagnetic layer 103 and a magnetization direction of the firstmagnetic layer 105. The insulatinglayer 104 is made of MgO and has a thickness of, for example, 1.3 nm. - The first
magnetic layer 105 is provided on the insulatinglayer 104 and contains a ferromagnetic material. The firstmagnetic layer 105 functions as a so-called “free layer” of which a magnetization direction can be changed in response to an external magnetic field as magnetic information. The firstmagnetic layer 105 is made of CoFeB and has a thickness of, for example, about 2.5 nm. - The
upper electrode layer 106 is an electrode member which is formed on the substrate B and has electrical conductivity. Theupper electrode layer 106 has a thickness of, for example, about 5 nm. Theetching mask 107 is formed on theupper electrode layer 106. Theetching mask 107 is formed in a shape according to a plane-view shape of theMRAM device 100. Theetching mask 107 is made of, for example, Ta (tantalum), TiN (titanium nitride), etc., and has a thickness of, for example, 50 nm. - Here, a manufacturing method of the
MRAM device 100 will be explained. TheMRAM device 100 is manufactured by using a processing system including a plasma processing apparatus and a film forming apparatus. Hereinafter, the plasma processing apparatus will be explained in detail.FIG. 2 is a cross sectional view showing the plasma processing apparatus used for manufacturing theMRAM device 100. - A
plasma processing apparatus 10 includes aprocessing chamber 12. Theprocessing chamber 12 has a substantially cylindrical shape, and a processing space S is partitioned and formed as an inner space thereof. Theplasma processing apparatus 10 includes a base 14 having a substantially circular plate shape within theprocessing chamber 12. Thebase 14 is provided under the processing space S. Thebase 14 is made of, for example, aluminum and serves as a second electrode. Thebase 14 is configured to absorb heat of anelectrostatic chuck 50 to be described later to cool theelectrostatic chuck 50 during a process. - Within the
base 14, acoolant path 15 is formed. Thecoolant path 15 is connected with a coolant inlet line and a coolant outlet line. Further, thebase 14 and theelectrostatic chuck 50 can be controlled to have a preset temperature by circulating an appropriate coolant, for example, cooling water, through thecoolant path 15. - In the example embodiment, the
plasma processing apparatus 10 further includes acylindrical holder 16 and a cylindrical supportingmember 17. Thecylindrical holder 16 is in contact with a side surface of thebase 14 and a peripheral portion of a bottom surface of the base 14 to hold thebase 14. The cylindrical supportingmember 17 is vertically extended from a bottom portion of theprocessing chamber 12, and is configured to support thebase 14 via thecylindrical holder 16. Theplasma processing apparatus 10 further includes afocus ring 18 mounted on a top surface of thecylindrical holder 16. Thefocus ring 18 may be made of, for example, silicon or quartz. - In the example embodiment, an
exhaust path 20 is formed between a side wall of theprocessing chamber 12 and the cylindrical supportingmember 17. At an upper portion or at the middle portion of theexhaust path 20, abaffle plate 22 is provided. Further, at a bottom portion of theexhaust path 20, anexhaust opening 24 is formed. Theexhaust opening 24 is partitioned and formed by anexhaust pipe 28 inserted into the bottom portion of theprocessing chamber 12. Theexhaust pipe 28 is connected with an exhaust device (exhaust unit) 26. Theexhaust device 26 includes a vacuum pump, and is configured to depressurize the processing space S within theprocessing chamber 12 to a preset vacuum level. At the side wall of theprocessing chamber 12, there is provided agate valve 30 configured to open and close a loading/unloading opening for a target object (substrate) W. - The
base 14 is electrically connected with a second high frequency power supply (second power supply unit) 32 for plasma generation via amatching unit 34. The second highfrequency power supply 32 is configured to apply a high frequency power having a second frequency (for example, 400 kHz) to the second electrode, i.e., thebase 14. - The
plasma processing apparatus 10 further includes therein ashower head 38. Theshower head 38 is provided above the processing space S. Theshower head 38 includes anelectrode plate 40 and anelectrode supporting member 42. - The
electrode plate 40 is a conductive plate having a substantially circular plate shape, and serves as a first electrode. Theelectrode plate 40 is electrically connected with a first high frequency power supply (first power supply unit) 35 for plasma generation via amatching unit 36. The first highfrequency power supply 35 is configured to apply a high frequency power having a first frequency (for example, 60 MHz) to theelectrode plate 40. When the high frequency powers are applied to thebase 14 and theelectrode plate 40 from the second highfrequency power supply 32 and the first highfrequency power supply 35, respectively, a high frequency electric field is generated in the space, i.e., the processing space S, between the base 14 and theelectrode plate 40. - In the
electrode plate 40, multiple gas discharge holes 40 h are formed. Theelectrode plate 40 is detachably supported on theelectrode supporting member 42. Within theelectrode supporting member 42, abuffer room 42 a is formed. Theplasma processing apparatus 10 further includes agas supply unit 44. A gas inlet opening 25 of thebuffer room 42 a is connected with thegas supply unit 44 via agas supply line 46. Thegas supply unit 44 is configured to supply a processing gas into the processing space S. Thegas supply unit 44 can supply various kinds of etching gases. In theelectrode supporting member 42, multiple holes respectively communicating with the multiple gas discharge holes 40 h are formed. The multiple holes also communicate with thebuffer room 42 a. Therefore, a gas supplied from thegas supply unit 44 is introduced into the processing space S through thebuffer chamber 42 a and the gas discharge holes 40 h. Further, in order to control a radical distribution, a flow rate FC of the processing gas at a central region of the target object W and a flow rate FE of the processing gas at a peripheral portion of the target object W may be controlled. - In the example embodiment, there is provided a magnetic
field forming device 48 annularly or concentrically extended at a ceiling portion of theprocessing chamber 12. The magneticfield forming device 48 is configured to facilitate the start of the high frequency electric discharge (plasma ignition) in the processing space S and stably maintain the electric discharge. - In the example embodiment, the
electrostatic chuck 50 is provided on a top surface of thebase 14. Theelectrostatic chuck 50 includes anelectrode 52 and a pair of insulatingfilms films electrode 52 is a conductive film, and is provided between the insulatingfilm 54 a and the insulatingfilm 54 b. Theelectrode 52 is connected with aDC power supply 56 via a switch SW. When a DC voltage is applied to theelectrode 52 from theDC power supply 56, a Coulomb force is generated and the target object W is attracted to and held on theelectrostatic chuck 50 by the Coulomb force. Within theelectrostatic chuck 50, a heater 53 as a heating member is embedded and configured to heat the target object W to a preset temperature. The heater 53 is connected with a heater power supply via a wiring. Thebase 14 and theelectrostatic chuck 50 serve as a mounting table 70. - In the example embodiment, the
plasma processing apparatus 10 further includesgas supply lines gas supply units gas supply unit 62 is connected with thegas supply line 58. Thegas supply line 58 is extended to a top surface of theelectrostatic chuck 50 and annularly extended at a central region of the top surface. The heat transfergas supply unit 62 is configured to supply a heat transfer gas such as a He gas between the top surface of theelectrostatic chuck 50 and a rear surface of the target object W. Further, the heat transfergas supply unit 64 is connected with thegas supply line 60. Thegas supply line 60 is extended to the top surface of theelectrostatic chuck 50 and annularly extended at the top surface to surround thegas supply line 58. The heat transfergas supply unit 64 is configured to supply a heat transfer gas such as a He gas between the top surface of theelectrostatic chuck 50 and the rear surface of the target object W. - In the example embodiment, the
plasma processing apparatus 10 may further include acontrol unit 66. Thecontrol unit 66 is connected with theexhaust device 26, the switch SW, the second highfrequency power supply 32, the matchingunit 34, the first highfrequency power supply 35, the matchingunit 36, thegas supply unit 44, and the heat transfergas supply units control unit 66 is configured to transmit a control signal to each of theexhaust device 26, the switch SW, the second highfrequency power supply 32, the matchingunit 34, the first highfrequency power supply 35, the matchingunit 36, thegas supply unit 44, and the heat transfergas supply units control unit 66, an exhaust by theexhaust device 26, an opening and closing of the switch SW, a power supply from the second highfrequency power supply 32, an impedance control by the matchingunit 34, a power supply from the first highfrequency power supply 35, an impedance control by the matchingunit 36, a processing gas supply by thegas supply unit 44, and a heat transfer gas supply by each of the heat transfergas supply units - In this
plasma processing apparatus 10, a processing gas is supplied from thegas supply unit 44 into the processing space S. Further, between theelectrode plate 40 and thebase 14, i.e., in the processing space S, a high frequency electric field is generated. Thus, plasma is generated in the processing space S, and the target object W is etched with radicals of the element contained in the processing gas. - Hereinafter, a plasma processing method performed in the above-described
plasma processing apparatus 10 will be explained.FIG. 3 is a flow chart showing a plasma processing method in accordance with the example embodiment. In the plasma processing method in accordance with the example embodiment, as depicted inFIG. 3 , at block S1, the target object W is prepared and mounted on theelectrostatic chuck 50 in theprocessing chamber 12.FIG. 4 shows an example of the target object W formed during the manufacturing process of theMRAM device 100. This target object W is a multilayered structure including thelower electrode layer 101, the pinninglayer 102, the secondmagnetic layer 103, the insulatinglayer 104, the firstmagnetic layer 105, and theupper electrode layer 106 stacked on the substrate B. On theupper electrode layer 106, theetching mask 107 having a preset plane-view shape is formed. Hereinafter, the plasma processing method in accordance with the example embodiment using, for example, the target object W depicted inFIG. 4 will be explained. - At block S2 (First Etching Process), the
upper electrode 106 is etched. Any etching gas can be used in this case. For example, Cl2, CH4, He, N2, Ar, and the like may be used. Then, a first processing gas containing chlorine (Cl2) is supplied into theprocessing chamber 12 from thegas supply unit 44 to generate plasma, and the target object W is etched. The first etching gas may further contain an inert gas such as He, N2, and Ar, and H2. At block S2, a region of the firstmagnetic layer 105 that is not covered by theetching mask 107 reacts with chlorine to be etched with the first processing gas. However, since MgO does not react with chlorine, the insulatinglayer 104 is not etched. Therefore, at block S2, the etching is stopped on a surface of the insulatinglayer 104. - At block S2, when the first
magnetic layer 105 is etched with the first processing gas, a material to be etched reacts with the first processing gas, so that a by-product is produced. This by-product is produced from a reaction between CoFeB of the firstmagnetic layer 105 and Cl2 contained in the first processing gas, as expressed by the following formula (1). -
CoFeB+Cl2→CoCl2 (1) - This by-product as a residue Z adheres to side walls of the first
magnetic layer 105, theupper electrode layer 106, and theetching mask 107, as depicted inFIG. 5 . Since the residue Z contains a conductive material, it may cause a leakage current in the MRAM device. - Hereinafter, there will be provided an example of processing conditions where the process of block S2 is carried out in the
plasma processing apparatus 10. - (Block S2)
- Pressure inside processing space S: 10 mTorr (1.33 Pa)
- Power from first high frequency power supply 35: 100 W
- Power from second high frequency power supply 32: 300 W
- Flow rate of first processing gas
-
- N2 gas: 250 sccm
- Cl2 gas: 50 sccm
- Radical distribution control (RDC) FC/FE: 50
- Processing time: 10 seconds
- In the plasma processing method in accordance with the example embodiment, at subsequent block S3 (Second Etching Process), a second processing gas containing hydrogen (H2) is supplied into the
processing chamber 12 from thegas supply unit 44 to generate plasma, so that the residue Z produced at block S2 is removed. The second processing gas may further contain an inert gas such as He, N2, and Ar. - At block S3, within the
processing chamber 12, CoCl2 in the residue Z and H2 contained in the second processing gas make a reaction as expressed by the following formula (2). -
CoCl2+H2→HCl+Co (2) - At block S3, as shown in the formula (2), CoCl2 in the residue Z and H2 contained in the second processing gas make a reaction, so that HCl and Co are produced. Among the products produced at block S3, HCl is volatilized to be discharged to the outside. Further, Co produced at block S3 has a porous shape and is sputtered with, for example, N2 or Ar to be separated and removed. At block S3, as depicted in
FIG. 6 , the residue Z is removed from the side walls of theupper electrode layer 106, the firstmagnetic layer 105, and theetching mask 107. - Hereinafter, there will be provided an example of processing conditions where the process of block S3 is carried out in the
plasma processing apparatus 10. In the following processing conditions, block S3 may be divided into two blocks S3A and S3B. - (Block S3A)
- Pressure inside processing space S: 30 mTorr (4.00 Pa)
- Power from first high frequency power supply 35: 200 W
- Power from second high frequency power supply 32: 0 W
- Flow rate of second processing gas
-
- H2 gas: 400 sccm
- N2 gas: 100 sccm
- Radical distribution control (RDC) FC/FE: 50
- Processing time: 2 seconds
- (Block S3B)
- Pressure inside processing space S: 30 mTorr (4.00 Pa)
- Power from first high frequency power supply 35: 200 W
- Power from second high frequency power supply 32: 1000 W
- Flow rate of second processing gas
-
- H2 gas: 400 sccm
- N2 gas: 100 sccm
- Radical distribution control (RDC) FC/FE: 50
- Processing time: 10 seconds
- In the plasma processing method in accordance with the example embodiment, at subsequent block S4 (Coating Process), as depicted in
FIG. 7 , a surface of the target object W is coated with the insulatingfilm 108. By way of example, the target object W is transferred to a film forming apparatus (for example, RLSA apparatus or CVD apparatus) and the film is formed. This insulatingfilm 108 may be formed by using, for example, SiN or SiO2. Then, the target object W is returned to theplasma processing apparatus 10 depicted inFIG. 2 , and the insulatingfilm 108 is etched such that the insulatingfilm 108 remains at the side walls of the firstmagnetic layer 105,upper electrode layer 106, andetching mask 107. - In the plasma processing method in accordance with the example embodiment, at subsequent block S5 (Third Etching Process), a third processing gas containing methane (CH4) is supplied into the
processing chamber 12 from thegas supply unit 44 to generate plasma, so that the insulatinglayer 104 and the secondmagnetic layer 103 are etched. The target object W etched at block S5 is illustrated inFIG. 8 . The third processing gas may further contain other gases such as an inert gas including He, N2, Ar or the like, or a gas containing a carbonyl group, H2 or the like other than methane. At block S5, regions of the insulatinglayer 104, the secondmagnetic layer 103, and the pinninglayer 102 that are not covered by theetching mask 107 and the insulatingfilm 108 are etched with the third processing gas. In this case, a metal contained in the etching target layers becomes an organic metal to be volatilized and exhausted. Thus, the pinninglayer 102, the secondmagnetic layer 103, and the insulatinglayer 104 are etched to have a width greater than that of the firstmagnetic layer 105, theupper electrode layer 106, and theetching mask 107 by a width of the insulatingfilm 108 remaining at the side walls of the firstmagnetic layer 105, theupper electrode layer 106, and theetching mask 107. - In the plasma processing method in accordance with the example embodiment, at subsequent block S6, a fourth processing gas is supplied into the
processing chamber 12 from thegas supply unit 44 to generate plasma, so that thelower electrode layer 101 is etched. The target object W etched at block S6 is illustrated inFIG. 9 . The fourth processing gas may be the same processing gas as the third processing gas. That is, the fourth processing gas may contain an inert gas such as He, N2, Ar or the like, or a gas containing a carbonyl group, CH4, and H2. At block S6, a region of thelower electrode layer 101 that is not covered by theetching mask 107 and the insulatingfilm 108 is etched with the fourth processing gas. In this case, a metal contained in the etching target layer becomes an organic metal to be volatilized and exhausted. Thus, thelower electrode layer 101 is etched to have the width greater than that of the firstmagnetic layer 105, theupper electrode layer 106, and theetching mask 107 by the width of the insulatingfilm 108 remaining at the side walls of the firstmagnetic layer 105, theupper electrode layer 106, and theetching mask 107. - When the process of block S6 is ended, the plasma process depicted in
FIG. 3 is ended. In this way, a MRAM device is manufactured in a desired shape from the target object W having a multilayered structure. Hereinafter, processing conditions where the plasma processing method is carried out in theplasma processing apparatus 10 will be explained in detail. - In the plasma processing method in accordance with the example embodiment, during the etching processes at blocks S2, S3, S5, and S6, a power having a frequency of 1 MHz or less as a second frequency may be applied from the second high
frequency power supply 32 to the second electrode. In particular, a power having a frequency of 400 kHz or less as the second frequency may be applied from the second highfrequency power supply 32 to thebase 14. If a power having a relatively low frequency is applied to thebase 14, plasma is generated at a relatively upper space of the processing space S, i.e., a position spaced from the target object W, as compared with a case of applying a power having a relatively high frequency to thebase 14. Thus, a cathode drop voltage Vdc is increased, so that an ion can be vertically attracted by the second electrode. As a result, verticality of the etching profile is improved. Further, since plasma is not generated right above the target object W, it is possible to suppress dissociation of an organic metal complex separated from the target object W at blocks S5 and S6. - Further, in the plasma processing method in accordance with the example embodiment, during the etching processes at blocks S2, S3, S5, and S6, particularly, at blocks S5 and S6, the first high
frequency power supply 35 may apply a power of 100 W to 300 W to theelectrode plate 40 to generate plasma in theprocessing chamber 12. Thus, since the plasma is generated at a low dissociation region, the secondmagnetic layer 103 containing CoFeB can be plasma-etched to be exhausted in the form of an organic metal complex having a large molecular structure. - Furthermore, in the plasma processing method in accordance with the example embodiment, during the etching processes at blocks S2, S3, S5, and S6, a pressure inside the processing space S may be set to be 10 mTorr to 30 mTorr (1.33 Pa to 4.00 Pa). By setting the pressure inside the processing space S to be 30 mTorr (4.00 Pa) or less, a density of plasma generated in the processing space S can be reduced, and an ion mean free path can be lengthened. As a result, the verticality of the etching profile can be improved. Meanwhile, by setting the pressure inside the processing space S to be 10 mTorr (1.33 Pa) or more, appropriate etching selectivity between the insulating
film 108 and the insulatinglayer 104 can be obtained. - Moreover, the
plasma processing apparatus 10 configured to perform the plasma processing method in the example embodiment may have a gap of, for example, 20 mm to 30 mm. Herein, the term “gap” refers to a height of the processing space S partitioned and formed by theprocessing chamber 12. By using theplasma processing apparatus 10 having such a relatively small gap, a sputtering effect can be increased so that the exhaust for a low residence time can be promoted. - According to the plasma processing method explained above, in the first etching process, the first processing gas containing Cl2 is supplied and plasma is generated, so that the first
magnetic layer 105 is etched, and then, the etching process is ended on the surface of the insulatinglayer 104. Here, Cl2 reacts with CoFeB contained in the firstmagnetic layer 105 but does not react with MgO contained in the insulatinglayer 104. Thus, the etching selectivity between the firstmagnetic layer 105 containing CoFeB and the insulatinglayer 104 containing MgO can be improved. Further, according to this plasma processing method, in the second etching process, the residue Z adhering to the side walls of the firstmagnetic layer 105 and the top surface of the insulatinglayer 104 is removed with the etching gas containing H2. Thus, the verticality of the firstmagnetic layer 105 can be improved, and it is possible to suppress the residue Z from being dispersed and adhering to the side walls of the insulatinglayer 104 in the etching of the insulatinglayer 104 to be described later. Therefore, according to the plasma processing method in accordance with the example embodiment, it is possible to improve characteristics of theMRAM device 100 by suppressing the leakage current. - Further, since the second processing gas further contains at least one of N2, Ar, and He, it is possible to surely remove the residue Z adhering to the side walls of first
magnetic layer 105 and the top surface of the insulatinglayer 104. - Furthermore, since the plasma etching method further includes the coating process in which the surface of the target object W is coated with the insulating
film 108 after the second etching process, it is possible to surely suppress the residue Z from adhering to the side walls of the insulatinglayer 104 in the subsequent process. - Moreover, since the plasma etching method further includes the third etching process in which the third processing gas containing CH4 is supplied into the
processing chamber 12 to generate plasma and the insulatinglayer 104 and the secondmagnetic layer 103 are etched after the coating process, it is possible to manufacture a MRAM device from the target object W. - Besides, the
plasma processing apparatus 10 depicted inFIG. 2 includes theelectrode plate 40 provided within theprocessing chamber 12; the base 14 provided to face theelectrode plate 40; the first highfrequency power supply 35 configured to apply the power of 60 MHz to theelectrode plate 40; and the second highfrequency power supply 32 configured to apply the power of 400 kHz to thebase 14. In thisplasma processing apparatus 10, the plasma is generated within theprocessing chamber 12 by applying the power having a frequency of 400 kHz from the second highfrequency power supply 32 to thebase 14. In this case, since the power having a relatively low frequency is applied to thebase 14, the plasma is generated at a position spaced from the target object W. Thus, an ion can be vertically attracted by thebase 14, so that the verticality of the side wall of the target object W can be improved accordingly. - In the plasma processing method, plasma is generated within the
processing chamber 12 by applying a power of 100 W to 300 W from the first highfrequency power supply 35 to theelectrode plate 40. Therefore, since a relatively low power is applied to theelectrode plate 40, low-density plasma is generated at a lower limit of the margin of plasma ignition, and for example, the etched insulatinglayer 104 or secondmagnetic layer 103 can be discharged to the outside in the form of an organic metal complex having a large molecular structure. - The
plasma processing apparatus 10 further includes theexhaust device 26 configured to depressurize theprocessing space 12 to a desired pressure level; and thecontrol unit 66 configured to control theexhaust device 26. In the plasma processing method, thecontrol unit 66 controls theexhaust device 26 to set a pressure inside the processing space to be 10 mTorr to 30 mTorr (1.33 Pa to 4.00 Pa). By setting the pressure inside the processing space S to be low, the plasma density generated in the processing space S can be reduced, and the ion mean free path is lengthened, so that the verticality of the etching profile can be improved. - In the plasma processing method, the processing space S has the gap of 20 mm to 30 mm. Therefore, the sputtering effect can be increased, so that the exhaust for a low residence time (short staying time) can be promoted.
- The present disclosure has been explained in detail with reference to the example embodiments. However, the present disclosure is not limited to the above example embodiments. The present disclosure can be modified and changed in various ways within the scope of the present disclosure.
- By way of example, in the
plasma processing apparatus 10 of the above example embodiment, theelectrode plate 40 is provided at the upper portion of theplasma processing apparatus 10, and the first highfrequency power supply 35 applies the high frequency power from above the processing space S. However, theelectrode plate 40 may be provided at a lower portion of theplasma processing apparatus 10, and the first highfrequency power supply 35 may apply the high frequency power from below the processing space S. - Further, the multilayered structure may include the
lower electrode layer 101, the pinninglayer 102, the secondmagnetic layer 103, the insulatinglayer 104, the firstmagnetic layer 105, theupper electrode layer 106, and theetching mask 107. - Hereinafter, the present disclosure will be explained in more detail based on experimental examples and comparative examples, but the present disclosure is not limited to the experimental examples below.
- (Observation of Etching Selectivity and Removal of Residue Z)
- In a first experimental example, a target object W is etched with a first processing gas in the
plasma processing apparatus 10 depicted inFIG. 2 . The target object W used herein has a thickness of 70.8 nm from the top surface of the substrate B to the top surface of the insulatinglayer 104. Then, a surface of the target object W after the etching process is observed with an electron microscope. In the first experimental example, the etching process is divided into four sub-processes. Each of the four sub-processes is carried out under the following processing conditions. - (First Sub-Process)
- Pressure inside processing space S: 30 mTorr (4.00 Pa)
- Power from first high frequency power supply 35: 200 W
- Power from second high frequency power supply 32: 0 W
- Flow rate of first processing gas
-
- N2 gas: 200 sccm
- CH4 gas: 50 sccm
- Cl2 gas: 50 sccm
- Radical distribution control (RDC) FC/FE: 50
- Processing time: 2 seconds
- (Second Sub-Process)
- Pressure inside processing space S: 30 mTorr (4.00 Pa)
- Power from first high frequency power supply 35: 200 W
- Power from second high frequency power supply 32: 300 W
- Flow rate of first processing gas
-
- N2 gas: 200 sccm
- CH4 gas: 50 sccm
- Cl2 gas: 50 sccm
- Radical distribution control (RDC) FC/FE: 50
- Processing time: 2 seconds
- (Third Sub-Process)
- Pressure inside processing space S: 20 mTorr (2.67 Pa)
- Power from first high frequency power supply 35: 200 W
- Power from second high frequency power supply 32: 300 W
- Flow rate of first processing gas
-
- N2 gas: 200 sccm
- CH4 gas: 50 sccm
- Cl2 gas: 50 sccm
- Radical distribution control (RDC) FC/FE: 50
- Processing time: 70 seconds
- (Fourth Sub-Process)
- Pressure inside processing space S: 10 mTorr (1.33 Pa)
- Power from first high frequency power supply 35: 100 W
- Power from second high frequency power supply 32: 300 W
- Flow rate of first processing gas
-
- N2 gas: 250 sccm
- Cl2 gas: 50 sccm
- Radical distribution control (RDC) FC/FE: 50
- Processing time: 10 seconds
-
FIG. 10A provides a schematic diagram of a SEM image of the surface of the etched target object W in the first experimental example. As shown inFIG. 10A , it is observed that a residue Z adheres to the surface of the etched target object W in the first experimental example. In the first experimental example, the thickness of the etched target object W is 78.1 nm. - In a second experimental example, the target object W etched in the first experimental example is further etched with a second processing gas in the
plasma processing apparatus 10 depicted inFIG. 2 . Then, the surface of the target object W after the etching process is observed with the electron microscope. In the second experimental example, the etching process is divided into two sub-processes. Each of the two sub-processes is carried out under the following processing conditions. - (First Sub-Process)
- Pressure inside processing space S: 30 mTorr (4.00 Pa)
- Power from first high frequency power supply 35: 200 W
- Power from second high frequency power supply 32: 0 W
- Flow rate of second processing gas
-
- H2 gas: 400 sccm
- N2 gas: 100 sccm
- Radical distribution control (RDC) FC/FE: 50
- Processing time: 2 seconds
- (Second Sub-Process)
- Pressure inside processing space S: 30 mTorr (4.00 Pa)
- Power from first high frequency power supply 35: 200 W
- Power from second high frequency power supply 32: 1000 W
- Flow rate of second processing gas
-
- H2 gas: 400 sccm
- N2 gas: 100 sccm
- Radical distribution control (RDC) FC/FE: 50
- Processing time: 10 seconds
-
FIG. 10B provides a schematic diagram of a SEM image of the surface of the etched target object W in the second experimental example. Further,FIG. 11 is a schematic diagram of a TEM image of a region (which is indicated by a dotted line inFIG. 10B ) of theMRAM device 100 obtained from the second experimental example. As shown inFIG. 10A andFIG. 11 , it is observed that the residue Z is removed from the surface of the target object W in the second experimental example. In the second experimental example, the thickness of the etched target object W is 70.8 nm. Thus, it is confirmed that the etching process is stopped on the top surface of the insulatinglayer 104. - (Observation of Low-Bias Frequency Effect)
- Hereinafter, there will be explained an experimental example in which the second frequency of the power supplied from the second high
frequency power supply 32 is changed. In a third experimental example, an etching process is carried out in the plasma processing apparatus depicted inFIG. 2 by applying a power having a frequency of 60 MHz from the first highfrequency power supply 35 to theelectrode plate 40 and applying a power having a frequency of 400 kHz from the second highfrequency power supply 32 to thebase 14. In the third experimental example, a processing time is set to be 120 seconds. As an etching gas, a gas containing H2, Ar, and CH4 is used. - In a first comparative example, an etching process is carried out in the plasma processing apparatus depicted in
FIG. 2 by applying a power having a frequency of 60 MHz from the first highfrequency power supply 35 to theelectrode plate 40 and applying a power having a frequency of 13 MHz from the second highfrequency power supply 32 to thebase 14. In the first comparative example, a processing time is set to be 100 seconds. The other processing conditions are the same as those of the third experimental example. -
FIG. 12A andFIG. 12B are schematic diagrams of SEM images of surfaces of target objects W etched in the third experimental example and the first comparative example, respectively. As depicted inFIG. 12A , in the target object W of the third experimental example, a side wall of theMRAM device 100 has a taper angle of 85.7°. Further, the target object W in the third experimental example has a thickness of 60.8 nm and a height of 140 nm. Further, as depicted inFIG. 12B , in the target object W of the first comparative example, a side wall of theMRAM device 100 has a taper angle of 76.0°. Further, the target object W in the third experimental example has a thickness of 56.9 nm and a height of 136 nm. In this way, in the third experimental example in which the high frequency power having the second frequency of 400 kHz is applied, it is observed that the etching process can be carried out with higher verticality, as compared with the first comparative example in which the high frequency power having the second frequency of 13 MHz is applied, when being etched to have the substantially same height. - (Observation of Low-Pressure Effect)
- Hereinafter, there will be explained an experimental example in which the pressure inside the processing space S is changed. In a fourth experimental example, the target object W is etched with the first processing gas and also etched with the second processing gas in the
plasma processing apparatus 10 depicted inFIG. 2 . Then, a surface of the target object W after the etching process is observed with the electron microscope. In the fourth experimental example, the etching process is divided into six sub-processes. Each of the six sub-processes is carried out under the following processing conditions. - (First Sub-Process)
- Pressure inside processing space S: 30 mTorr (4.00 Pa)
- Power from first high frequency power supply 35: 200 W
- Power from second high frequency power supply 32: 0 W
- Flow rate of first processing gas
-
- N2 gas: 200 sccm
- CH4 gas: 50 sccm
- Cl2 gas: 50 sccm
- Radical distribution control (RDC) FC/FE: 50
- Processing time: 2 seconds
- (Second Sub-Process)
- Pressure inside processing space S: 30 mTorr (4.00 Pa)
- Power from first high frequency power supply 35: 200 W
- Power from second high frequency power supply 32: 300 W
- Flow rate of first processing gas
-
- N2 gas: 200 sccm
- CH4 gas: 50 sccm
- Cl2 gas: 50 sccm
- Radical distribution control (RDC) FC/FE: 50
- Processing time: 2 seconds
- (Third Sub-Process)
- Pressure inside processing space S: 20 mTorr (2.67 Pa)
- Power from first high frequency power supply 35: 200 W
- Power from second high frequency power supply 32: 300 W
- Flow rate of first processing gas
-
- N2 gas: 200 sccm
- CH4 gas: 50 sccm
- Cl2 gas: 50 sccm
- Radical distribution control (RDC) FC/FE: 50
- Processing time: 70 seconds
- (Fourth Sub-Process)
- Pressure inside processing space S: 10 mTorr (1.33 Pa)
- Power from first high frequency power supply 35: 100 W
- Power from second high frequency power supply 32: 300 W
- Flow rate of first processing gas
-
- N2 gas: 250 sccm
- Cl2 gas: 50 sccm
- Radical distribution control (RDC) FC/FE: 50
- Processing time: 10 seconds
- (Fifth Sub-Process)
- Pressure inside processing space S: 30 mTorr (4.00 Pa)
- Power from first high frequency power supply 35: 200 W
- Power from second high frequency power supply 32: 0 W
- Flow rate of second processing gas
-
- H2 gas: 400 sccm
- N2 gas: 100 sccm
- Radical distribution control (RDC) FC/FE: 50
- Processing time: 2 seconds
- (Sixth Sub-Process)
- Pressure inside processing space S: 30 mTorr (4.00 Pa)
- Power from first high frequency power supply 35: 200 W
- Power from second high frequency power supply 32: 1000 W
- Flow rate of second processing gas
-
- H2 gas: 400 sccm
- N2 gas: 100 sccm
- Radical distribution control (RDC) FC/FE: 50
- Processing time: 20 seconds
- In a second comparative example, the target object W is etched under the same processing conditions as the fourth experimental example only except that a pressure inside the processing space S during the fourth sub-process is set to be 30 mTorr (4.00 Pa) and a processing time for the sixth sub-process is set to be 10 seconds.
-
FIG. 13A andFIG. 13B are schematic diagrams of SEM images of surfaces of the target objects W etched in the fourth experimental example and the second comparative example, respectively.FIG. 14 is a schematic diagram of a TEM image of the surface of the target object W etched in the fourth experimental example and the second comparative example. As shown inFIG. 13A andFIG. 14 , in the fourth experimental example, a thickness of the etched target object W is 76.7 nm. Further, as depicted inFIG. 13B , in the target object W after the etching process in the second comparative example, a thickness of the etched target object W in the third experimental example is 70.1 nm. Furthermore, as depicted inFIG. 13B , in the second comparative example, it is observed that theMRAM device 100 becomes narrower toward the end portion thereof by the etching. In the fourth experimental example, it is observed that theMRAM device 100 does not become narrower toward the end portion thereof but has the higher verticality of the etching profile. - (Observation of Low-Gap Effect)
- Hereinafter, there will be explained an experimental example in which the gap of the
plasma processing apparatus 10 is changed. In a fifth experimental example, the target object W is etched in theplasma processing apparatus 10 having the gap of 25 mm. In the fifth experimental example, the target object W is etched under the following processing conditions. - Pressure inside processing space S: 6 mTorr (0.80 Pa)
- Power from first high frequency power supply 35: 500 W
- Power from second high frequency power supply 32: 100 W
- Flow rate of processing gas
-
- CO2 gas: 34 sccm
- CH4 gas: 26 sccm
- H2 gas: 150 sccm
- Ar gas: 50 sccm
- He gas: 10 sccm
- Radical distribution control (RDC) FC/FE: 50
- Processing time: 600 seconds
- In a third comparative example, the target object W is etched in the
plasma processing apparatus 10 having the gap of 35 mm. In the third comparative example, the target object W is etched under the following processing conditions. - Pressure inside processing space S: 6 mTorr (0.80 Pa)
- Power from first high frequency power supply 35: 500 W
- Power from second high frequency power supply 32: 100 W
- Flow rate of processing gas
-
- CO2 gas: 30 sccm
- CH4 gas: 25 sccm
- H2 gas: 150 sccm
- Ar gas: 50 sccm
- He gas: 10 sccm
- Radical distribution control (RDC) FC/FE: 50
- Processing time: 600 seconds
- After performing the etching process under the above-described processing conditions, SEM images of the target objects W obtained from the fifth experimental example and the third comparative example are observed, and dimensions of the target objects W are measured. In the
MRAM device 100 obtained from the fifth experimental example, a difference (CD) between a width of the firstmagnetic layer 105 and a width of thelower electrode layer 101 is 1.9 nm, and a difference (CD) between a width of theetching mask 107 and the width of thelower electrode layer 101 is 9.2 nm. Meanwhile, in theMRAM device 100 obtained from the third comparative example, a difference (CD) between a width of the firstmagnetic layer 105 and a width of thelower electrode layer 101 is 9.3 nm, and a difference (CD) between a width of theetching mask 107 and a width of thelower electrode layer 101 is 25.6 nm. As the CD decreases, the side wall of theMRAM device 100 is further vertically formed. Thus, in the fifth experimental example, it is observed that the residue Z is removed and the etching process is carried out with the higher verticality, as compared with the third comparative example. -
-
- 10: Plasma processing apparatus
- 12: Processing chamber
- 14: Base (Second electrode)
- 26: Exhaust device
- 32: Second high frequency power supply (Second power supply unit)
- 35: First high frequency power supply (First power supply unit)
- 40: Electrode plate (First electrode)
- 100: MRAM device
- 101: Lower electrode layer
- 102: Pinning layer
- 103: Second magnetic layer
- 104: Insulating layer
- 105: First magnetic layer
- 106: Upper electrode layer
- 107: Etching mask
- 108: Insulating film
- S: Processing space
- W: Target object
- Z: Residue
Claims (10)
1. A plasma processing method of etching a multilayered material having a structure in which a first magnetic layer and a second magnetic layer are stacked with an insulating layer interposed therebetween, by using a plasma processing apparatus including a processing chamber in which a processing space for plasma generation is partitioned and formed; and a gas supply unit of supplying a processing gas into the processing space, the plasma processing method comprising:
a first etching process in which the first magnetic layer is etched by supplying a first processing gas into the processing chamber and generating plasma, and the first etching process is stopped on a surface of the insulating layer; and
a second etching process in which a residue produced in the first etching process is removed by supplying a second processing gas into the processing chamber and generating plasma,
wherein the first magnetic layer and the second magnetic layer contain CoFeB,
the first processing gas contains Cl2, and
the second processing gas contains H2.
2. The plasma processing method of claim 1 ,
wherein the second processing gas further contains at least one of N2, Ar, and He.
3. The plasma processing method of claim 1 , further comprising:
a coating process in which a surface of the multilayered material is coated with an insulating film after the second etching process.
4. The plasma processing method of claim 3 , further comprising:
a third etching process in which the insulating layer and the second magnetic layer are etched by supplying a third processing gas into the processing chamber and generating plasma, after the coating process,
wherein the third processing gas contains CH4.
5. The plasma processing method of claim 1 ,
wherein the plasma processing apparatus further includes a first electrode provided within the processing chamber; a second electrode provided to face the first electrode; a first power supply unit configured to apply a power having a first frequency to the first electrode; and a second power supply unit configured to apply a power having a second frequency to the second electrode, and
the plasma is generated within the processing chamber by applying a power having 1 MHz or less as the second frequency from the second power supply unit to the second electrode.
6. The plasma processing method of claim 5 ,
wherein the plasma is generated within the processing chamber by applying a power having 400 kHz or less as the second frequency from the second power supply unit to the second electrode.
7. The plasma processing method of claim 4 ,
wherein the plasma is generated within the processing chamber by applying a power of 100 W to 300 W from the first power supply unit to the first electrode.
8. The plasma processing method of claim 1 ,
wherein the plasma processing apparatus further includes an exhaust unit configured to depressurize the processing space to a predetermined pressure level; and a control unit configured to control the exhaust unit, and
the control unit is configured to control the exhaust unit to set a pressure inside the processing space to be in a range of 10 mTorr to 30 mTorr (1.33 Pa to 4.00 Pa).
9. The plasma processing method of claim 1 ,
wherein the processing space has a gap of 20 mm to 30 mm.
10. A plasma processing apparatus of etching a multilayered material having a structure in which a first magnetic layer and a second magnetic layer are stacked with an insulating layer interposed therebetween, the plasma processing apparatus comprising:
a processing chamber in which a processing space for plasma generation is partitioned and formed;
a gas supply unit configured to supply a processing gas into the processing space; and
a control unit configured to control the gas supply unit,
wherein under the control of the control unit, the first magnetic layer is etched by supplying a first processing gas into the processing chamber and generating plasma, and then, the etching is stopped on a surface of the insulating layer; and a residue produced in the etching with the first processing gas is removed by supplying a second processing gas into the processing chamber and generating plasma,
the first magnetic layer and the second magnetic layer contain CoFeB,
the first processing gas contains Cl2, and
the second processing gas contains H2.
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US14/387,655 US9660182B2 (en) | 2012-04-26 | 2013-04-22 | Plasma processing method and plasma processing apparatus |
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PCT/JP2013/061806 WO2013161769A1 (en) | 2012-04-26 | 2013-04-22 | Plasma processing method and plasma processing apparatus |
US14/387,655 US9660182B2 (en) | 2012-04-26 | 2013-04-22 | Plasma processing method and plasma processing apparatus |
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JP (1) | JP6096762B2 (en) |
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Cited By (3)
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US11276816B2 (en) | 2018-06-20 | 2022-03-15 | Hitachi High-Tech Corporation | Method of manufacturing magnetic tunnel junction and magnetic tunnel junction |
US11312100B2 (en) | 2015-12-28 | 2022-04-26 | 3M Innovative Properties Company | Article with microstructured layer |
US11407196B2 (en) | 2015-12-28 | 2022-08-09 | 3M Innovative Properties Company | Article with microstructured layer |
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JP6400425B2 (en) * | 2014-10-15 | 2018-10-03 | 東京エレクトロン株式会社 | Method for etching a multilayer film |
JP6542053B2 (en) * | 2015-07-15 | 2019-07-10 | 株式会社東芝 | Plasma electrode structure and plasma induced flow generator |
US10361122B1 (en) | 2018-04-20 | 2019-07-23 | Taiwan Semiconductor Manufacturing Company, Ltd. | Processes for reducing leakage and improving adhesion |
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WO2011048746A1 (en) * | 2009-10-23 | 2011-04-28 | 株式会社アルバック | Method for manufacturing master disk for magnetic transfer |
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- 2013-04-22 KR KR1020147026698A patent/KR102056751B1/en active IP Right Grant
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- 2013-04-22 WO PCT/JP2013/061806 patent/WO2013161769A1/en active Application Filing
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US11312100B2 (en) | 2015-12-28 | 2022-04-26 | 3M Innovative Properties Company | Article with microstructured layer |
US11407196B2 (en) | 2015-12-28 | 2022-08-09 | 3M Innovative Properties Company | Article with microstructured layer |
US11276816B2 (en) | 2018-06-20 | 2022-03-15 | Hitachi High-Tech Corporation | Method of manufacturing magnetic tunnel junction and magnetic tunnel junction |
US11678583B2 (en) | 2018-06-20 | 2023-06-13 | Hitachi High-Tech Corporation | Method of manufacturing magnetic tunnel junction and magnetic tunnel junction |
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WO2013161769A1 (en) | 2013-10-31 |
US9660182B2 (en) | 2017-05-23 |
KR20150014434A (en) | 2015-02-06 |
JPWO2013161769A1 (en) | 2015-12-24 |
JP6096762B2 (en) | 2017-03-15 |
KR102056751B1 (en) | 2019-12-17 |
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